1. Field of the Invention
The present invention generally relates to introducer valves for surgical procedures, and more particularly, provides a pressure actuated valve which can maintain hemostasis around surgical instruments having a wide variety of cross-sectional diameters.
Introducer valves are used in a wide variety of minimally invasive and conventional surgical procedures. For example, laparoscopic and arthroscopic surgical procedures are often performed through trocar assemblies which include introducer valves. After a rigid trocar tube is inserted to provide access to a body cavity, surgical implements or tools are inserted into and withdrawn from a sealing valve located at a proximal end of the trocar tube. The introducer valve generally prevents fluid from inadvertently leaving or entering the body cavity through the trocar tube.
Current introducer valves generally fall into two basic categories: passive and active. A passive valve generally relies on the deformation of a resilient sealing body by the implement inserted through the valve to form the desired fluid tight seal. Active surgical valves include a mechanism that moves a sealing body into contact with the traversing implement.
A wide variety of passive and active surgical valve structures have been proposed. While these structures have met with varying degrees of success and acceptance, they generally have suffered from a common disadvantage: sealing bodies (whether passive or active) which seal effectively over a wide variety of cross-sectional diameters tend to impose substantial frictional forces on at least some sizes of traversing implements.
In fact, despite the wide variety of introducer valves which have been proposed, the use of simple fixed o-rings or grommets remains common. While these simple sealing devices accommodate only a very narrow range of surgical implement diameters, the seals provided within that range are reliable and the friction forces are light.
Recently, endovascular surgical procedures have been developed which place even more stringent demands on introducer valves. Of specific interest to the present invention, the endovascular placement of vascular stents, grafts, stent-grafts, and other endoluminal prostheses for the treatment of abdominal aortic aneurysms and other vascular diseases has been proposed. Such endovascular prosthetic placement will generally require the use of relatively large prosthetic deployment catheters, typically having an outer diameter in the range from about 4 mm to 10 mm. These large deployment catheters will require correspondingly large introducer sheaths, typically having an internal lumen diameter which is at least slightly larger than the outer diameter of the deployment catheter. These large sheaths will generally provide direct access to the major arteries of the vascular system, and will thus be subjected to relatively high blood flow rates and pressures. The target sites for deployment of these protheses, however, will often be at a considerable distance from the vascular access sites, and intravascular maneuvering to reach the target site is often performed with much smaller diameter implements. Work in connection with the present invention has shown that maintaining hemostasis while accessing the target site and deploying the endovascular prostheses can be problematic.
An exemplary endovascular procedure will involve deployment of endovascular prostheses to isolate abdominal aortic aneurysms. Access will generally be provided either through the femoral artery and beyond the hypogastric branch and the aorto iliac junction, or down through the subclavian artery, through the aortic arch, and into the thoracic aorta. In either case, the path will generally first be negotiated by flexible intravascular guidewires having very small diameters. Ideally, the hemostasis valve should allow delicate maneuvering of both the very small vascular guidewires and the large delivery catheters, preferably while maintaining effective hemostasis throughout the positioning and deployment procedure.
For these reasons, it would be desirable to provide improved hemostatic valves for use in endovascular, laparoscopic, and other surgical procedures. Such valves should preferably seal over a wide range of surgical implement diameters, preferably without imposing the high frictional forces of known vascular valves, regardless of the cross-sectional size of the surgical implement traversing the valve.
2. Description of the Background Art
U.S. Pat. No. 5,366,478, describes an endoscopic surgical sealing device. In one embodiment, the device comprises an uninflatable toroid which is used to seal a trocar. U.S. Pat. Nos. 5,350,364, and 5,197,955 describe a trocar assembly having a seal member that is generally of hourglass shape, defining converging and diverging sidewalls that form a constricted center bore portion therebetween. Various alternative means are described to either increase or decrease the inner diameter of the center bore portion of the seal member.
U.S. Pat. No. 4,705,518, describes an artificial sphincter apparatus, operation of which is effected by a number of remote and proximate actuation means. U.S. Pat. No. 4,850,953, describes a gastrostomy valve provided with an expansible membrane or balloon which assumes a torroidal configuration to seal against the abdominal wall. U.S. Pat. No. 5,127,626, describes an apparatus for sealing around shafts or tubes of varying diameter. U.S. Pat. No. 5,158,553, describes a rotatably actuated constricting catheter valve. A trocar canula and catheter assembly which optionally includes an inflatable sealing bladder is described in U.S. Pat. No. 5,300,047.
An exemplary adjustable valve having a radially compressible sealing body is described in U.S. Pat. No. 5,338,313, while U.S. Pat. Nos. 5,209,737 and 5,279,597, are generally relevant.